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Basran J, Efimov I, Chauhan N, Thackray SJ, Krupa JL, Eaton G, Griffith GA, Mowat CG, Handa S, Raven EL. The mechanism of formation of N-formylkynurenine by heme dioxygenases. J Am Chem Soc 2011; 133:16251-7. [PMID: 21892828 PMCID: PMC3210546 DOI: 10.1021/ja207066z] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Indexed: 01/22/2023]
Abstract
Heme dioxygenases catalyze the oxidation of L-tryptophan to N-formylkynurenine (NFK), the first and rate-limiting step in tryptophan catabolism. Although recent progress has been made on early stages in the mechanism, there is currently no experimental data on the mechanism of product (NFK) formation. In this work, we have used mass spectrometry to examine product formation in a number of dioxygenases. In addition to NFK formation (m/z = 237), the data identify a species (m/z = 221) that is consistent with insertion of a single atom of oxygen into the substrate during O(2)-driven turnover. The fragmentation pattern for this m/z = 221 species is consistent with a cyclic amino acetal structure; independent chemical synthesis of the 3a-hydroxypyrroloindole-2-carboxylic acid compound is in agreement with this assignment. Labeling experiments with (18)O(2) confirm the origin of the oxygen atom as arising from O(2)-dependent turnover. These data suggest that the dioxygenases use a ring-opening mechanism during NFK formation, rather than Criegee or dioxetane mechanisms as previously proposed.
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Affiliation(s)
- Jaswir Basran
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Igor Efimov
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Nishma Chauhan
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Sarah J. Thackray
- EaStCHEM, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom
| | - James L. Krupa
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Graham Eaton
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Gerry A. Griffith
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Christopher G. Mowat
- EaStCHEM, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom
| | - Sandeep Handa
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Emma Lloyd Raven
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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Latifi R, Tahsini L, Kumar D, Sastry GN, Nam W, de Visser SP. Oxidative properties of a nonheme Ni(ii)(O2) complex: Reactivity patterns for C–H activation, aromatic hydroxylation and heteroatom oxidation. Chem Commun (Camb) 2011; 47:10674-6. [DOI: 10.1039/c1cc13993b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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